i think a high 70's-80ish ambient temp is fine. feeding him in a separate tub might be the issue and is probably stressing him out. also how are u prepping the f/t mouse? is it fully thawed and warm enough for him to recognize as prey? give him a couple days, warm up a nice rat and offer it to him in his tub when u see his head poking out of a hide or him roaming after dusk.